Factorials of Negative IntegersDate: 06/27/2002 at 02:21:04 From: Steven Subject: factorial Is it possible to compute the factorial of a negative number, e.g., (-4)! = ? Date: 06/28/2002 at 05:33:31 From: Doctor Floor Subject: Re: factorial Hi, Steven, Thanks for your question. Starting from the explanation for 0! in the Dr. Math FAQ, 0! = 1 http://mathforum.org/dr.math/faq/faq.0factorial.html if we try to extend this to -1, we find that (-1)! = 1/0 which means that (-1!) is undefined. Extending further to (-2)! etc. is thus impossible as well. The same FAQ mentions the Gamma function, which generalizes the idea of factorial to non-integer numbers. Note that this function also yields undefined values for negative integer factorials. If you have more questions, just write back. Best regards, - Doctor Floor, The Math Forum http://mathforum.org/dr.math/ |
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